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  • Author or Editor: H. Shen x
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Summary

Silica-gel column chromatography and preparative reversed-phase high-performance liquid chromatography (RP-HPLC) were sequentially employed for the isolation of two antioxidants including gallic acid and methyl gallate from Folium Toonea Sinensis. An RP-HPLC-UV method was then developed and validated to rapidly determine their content in this herb with ethyl gallate as internal standard. The quantitation was performed on an XBridge Shield RP18 column (150 mm × 4.6 mm, 5 μm) under 40°C. The mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution was driven at 1.0 mL min−1 under gradient elution, and 270 nm was selected to monitor the separation. To evaluate the fitness for purpose of the method and to investigate the difference in the content of analytes among different samples, the leaves collected from five production sites were analyzed. The newly established method is suitable for routine analysis of gallic acid and methyl gallate in the herb and, hence, can assist in its quality assessment. It was also found that not only the content of two antioxidants but also the ratio varied significantly among different geographical origins. In addition, three samples from Yantai, Zumadian, and Zhenjiang were distinguished as they have a much higher content ratio than the other two.

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Molecularly imprinted polymers (MIPs) were synthesized by imprinting a new template—S(-)-1,1′-binaphthalene-2,2′-diamine (S-DABN) and applied as chiral stationary phases for chiral separation of DABN racemates by high-performance liquid chromatography (HPLC). The influence of some key factors on the chiral recognition ability of MIPs, such as the type of functional monomers and porogen and the molar ratio of template to monomer, was systematically investigated. The chromatographic conditions, such as mobile phase composition, sample loading, and flow rate, were also measured. The chiral separation for DABN racemates under the optimum chromatographic conditions by using MIP chiral stationary phase (CSP) of P3, prepared with the S-DABN/MAA ratio = 1/4 and used acetonitrile (2 mL) and chloroform (4 mL) as porogen, showed the highest separation factor (2.14). Frontal analysis was used to evaluate affinity to the target molecule of MIPs. The binding sites (B t) of MIPs and dissociation constant (K d) were estimated as 4.56 μmol g−1 and 1.40 mmol L−1, respectively. In comparison with the previous studies, this approach had the advantages, such as the higher separation factor, easy preparation, and cost-effectiveness, it not only has the value for research but also has a potential in industrial application.

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To evaluate the quality of Fructus Arctii, an accurate and reliable method of high-performance liquid chromatography/diode array detection—electrospray ionization—mass spectrometry (HPLC/DAD—ESI—MS) was developed. Nine compounds, including chlorogenic acid, caffeic acid, trans-p-hydroxycinnamic acid, arctiin, arctignan A, ethyl caffeate, matairesinol, arctigenin, and lappaol B, were determined simultaneously in 19 batches of Fructus Arctii samples collected from different localities. Nineteen common peaks were identified or tentatively assigned by comparing their mass spectrometric data with reference compounds, self-established compound library, and published literatures. Also, the 19 common peaks were selected as characteristic peaks to assess the similarity of chromatographic fingerprinting of these samples. Moreover, hierarchical clustering analysis (HCA) and principal components analysis (PCA) were successfully applied to demonstrate the variability of samples. The results indicated the content of nine compounds that varied greatly among the samples, and 19 samples collected from different localities could be discriminated. Furthermore, chlorogenic acid, arctiin, and arctigenin were found to be chemical markers for evaluating the quality of Fructus Arctii.

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